So I'm using YUI to add some animations in my application triggered when a user clicks certain elements. However, I'm running into a common problem that is easily fixed with some poor coding, but I'm looking for a more elegant solution that's less error-prone.
Often, when the user clicks something, a DOM element is animated (using Y.Anim) and I subscribe to that animation's 'end' event to remove the element from the document after its animation has completed. Pretty standard stuff.
However, problems arise when the user decides to spam-click the element that triggers this event. If the element is going to be removed from the DOM when the animation ends, and the user triggers an event handler that fires off ANOTHER animation on the same element, this 2nd animation will eventually cause YUI to spit really nasty errors because the node it was animating on suddenly disappeared from the document. The quickest solution I've found for this is to just set some module/class-level boolean state like 'this.postAnimating' or something, and inside the event handler that triggers the animation, check if this is set to true, and if so, don't do anything. In the 'end' handler for the animation, set this state to false.
This solution is really, really not ideal for many reasons. Another possible solution is to detach the event handler for duration of the animation and re-attach it once the animation is complete. This is definitely a little better, but I still don't like having to do extra bookkeeping that I could easily forget to do if forgetting to do so leads to incomprehensible YUI errors.
What's an elegant and robust way to solve this problem without mucking up a multi-thousand-line Javascript file with bits and pieces of state?
Here's some example code describing the issue and my solution to it.
var popupShowing = false,
someElement = Y.one('...');
someElement.on("click", showPopUp)
var showPopup = function(e) {
if(!popupShowing) {
popupShowing = true;
var a = new Y.Anim({
node: someElement,
duration: 0.2,
...
});
a.on('end', function() {
someElement.remove(true);
popupShowing = false;
});
a.run();
}
}
So if the user clicks "someElement" many times, only one animation will fire. If I didn't use popupShowing as a guard, many animations on the same node would be fired if the user clicked quickly enough, but the subsequent ones would error out because someElement was removed when the first completed.
Have a look at the Transition API. It's more concise, and may very well do what you want out of the box.
someElement.transition({ opacity: 0, duration: 0.2 }, function () { this.remove(); });
// OR
someElement.on('click', function () { this.hide(true, { duration: 0.2 }); });
// OR
someElement.on('click', someElement.hide);
Personally, I haven't used Anim since Transition was added in 3.2.0. Transition uses CSS3 where supported (with hardware acceleration), and falls back to a JS timer for older browsers.
http://developer.yahoo.com/yui/3/examples/transition/transition-view.html
Edit: By popular demand, a YUI way:
myAnim.get('running')
tells you whether an animation is running. To use this you might have to restructure the way you call the event so the animation is in the right scope, for example:
YUI().use('anim', function (Y) {
var someElement = Y.one('...');
var a = new Y.Anim({
node: someElement,
duration: 0.2,
...
});
a.on('end', function() {
someElement.remove(true);
});
someElement.on('click', function() {
if (!a.get('running')) {
a.run();
}
});
});
jsFiddle Example
Previously I had said: I personally like the way jQuery handles this. In jQuery, each element has a queue for animation functions. During animations an "in progress" sentinel is pushed to the front for the duration of the animation so anything that doesn't want to step on an animation peeks at the front of the queue for "in progress" and decides what to do from there, e.g. do nothing, get in line, preempt the current animation, etc.
I don't know enough about YUI to tell you how to implement this, but I find it to be a very elegant solution.
Quick & dirty solution to this particular issue?
Attach your handlers using .once() instead
someElement.once("click", showPopUp)
Also suitable if you need the handler re-attached later, just call that line again when the animation is done. You could also store your state information on the node itself using setData/getData but that is just a panacea to the real problem of state tracking.
Also, +1 to Luke's suggestion to use Transition for DOM property animation, it's grand.
Related
I have a website that I am creating and there are different divs each with their own content. All of them are hidden except the main one that shows up on the homepage. The transitions are pretty long, and I like it that way, but the problem is that if somebody spams the navbar buttons it opens up all those divs ontop of each other. So to prevent that I want to temporarily disable the onClick for an <a></a> element. Then enable it after the transition is done. Currently I am able to disable it, but cannot find a way to re-enable it.
function disable(){
$(".bar").unbind();
$(".bar").removeAttr("onClick");
}
I know how to call a function after a certain amount of time, but what is the "enable" equivalent to the code in this function?
The exact opposite would be to set the onClick back on the element.
$('.bar').attr('onClick', function() { alert('blah'); });
or with vanilla js
document.querySelector(".bar")
.setAttribute('onClick', function() {...});
However, this is difficult to manage for many elements with the same functionality. It would be easier to have this entirely managed with javascript (and jQuery in this case).
function clickEvent(event) {
var self = $(this);
// Unbind the event
self.off(clickEvent);
// Click logic here
// Rebind event
self.on('click', clickEvent);
}
$('.bar').on('click', clickEvent);
Instead of disabling the event on the DOM, you can just add an extra piece of logic to your dynamic divs:
$('#mydiv').click(function() {
if(!inTransition())
// DO A THING
else
// DON'T DO A THING
});
As a side note: If you're doing a lot of dynamic DOM manipulation, you may want to look into using a data binding framework such as Angular or Knockout. jQuery is nice for simple DOM manipulations, but it can quickly become messy and hard to maintain if you're doing something complex (which it sounds like you are).
As somewhat of an extension to nmg49's answer, I'd like to provide a solution that's a little more in depth.
Essentially what you'll want to do is create a flag to determine whether or not you are currently transitioning, and cancel the onClick if it is true (disabling it after the transition is complete).
var isTransitioning = false;
$('.bar').onClick(function(){
if(isTransitioning) return;
isTransitioning = true;
// DO TRANSITION
});
Once the transition is complete, you simply set isTransitioning to false (either in a callback, or at the end of your onClick function; which ever one applies to your code).
This will ensure that, no matter how many times they click the button, they will not be able to transition if they're already in transition.
im looking for some javascript events that trigger at the start and at the end navigating via dragging on flot plots so that i can do some ajax updates, however, I've been looking around online for some code to help me. I've found a few things, most didn't work worked or had bugs.
The best thing I've found so far is an answer from DNS, however it has unintentional behavior, when you hold the mouse click button down and stop panning the event triggers.
var delay = null;
element.on("plotpan", function() {
if (delay) clearTimeout(delay);
delay = setTimeout(function() {
// do your stuff here
delay = null;
}, 500);
});
The navigate plugin should really pass the event on to you; then you could easily check the state of the mouse buttons in your handler.
Since it doesn't, you'll need to attach your own mousedown/mouseup listeners to the overlay canvas; the child of your plot placeholder with class 'flot-overlay'. You can use these to update a shared variable with the state of the left button, then check that value in your handler above.
I have an html ul list of 10,000+ elements and want to add custom hover tooltip events and do some other processing to each one. To do this on document.ready takes 2-3 seconds and freezes the browser. How can I do this asynchronously so that the browser doesn't freeze?
I've been reading about setTimeout, jQuery queue and deferred, but maybe I'm too dense to understand it all. This guy had interesting stuff http://erickrdch.com/2012/05/asynchronous-loop-with-jquery-deferred.html
Here's my each() loop that adds the hover.
$('#biglist li').each(function(index) {
$(this).hover(function(e){
...do stuff...
});
});
Thanks for your help.
why do you have it encased in a loop? try just applying hover to #biglist with .on(), and then delegating to each li:
$('#biglist').on('hover','li', function(){
// do crap
});
The .each() loop is likely wreaking havoc by doing processing on each item. As a side note, if you need to have different functions performed for mouseenter vs mouseleave, u need to use the XML format (using the .on() method is slightly different than the traditional .hover() method):
$('#biglist').on({
mouseenter: function(){
// do mouseenter crap
},
mouseleave: function(){
// do mouseleave crap
}
},'li');
Either way this should greatly reduce CPU consumption from processing.
You should bind it to #bigList using .on(), instead of on 10,000+ elements:
$('#bigList').on('hover', 'li', function(e) {
// ...
});
Browser JavaScript does not support true concurrency (apart from cutting-edge HTML5 features, that is) so you can't have one process run in the background while the page continue to work normally.
The best you can do AFAIK is to cut your processing code into chunks as small as possible, then execute them with setTimeout or setInterval, using a low value for delay (but preferably non-zero, so the rest of the page won't freeze).
Setting aside the fact that you don't need a different hover handler for each element, as others pointed out, if you need to do heavy processing of your received data (and such processing can't be done by the server) one way would be using a queue:
var queue = [];
setInterval(function() {
var next = queue.shift();
if ( next ) next();
},50);
...
$.each(lotsOfData, function(index, value) {
queue.push(function() {
// Code for processing the value
});
});
I've made a javascript menu with css and javascript. I've used some mootools (1.11 , the only version i can use).
The script runs on domready, it fetches a dom element, and adds functions (showmenu, hidemenu) on the mouseenter and mouseleave events. The dom element is three levels of nested ul/li`s.
Now I want to add a delay on the menu of 500 ms when one hovers over the menu for the first time, and again when the users leaves the menu (so that the user has half a second time to get back to the menu).
I dont know how to keep track of the events, and cancel them. My knowledge of javascript is not good enough to know where to start. Can anyone give me an example how i should create this? Not really looking for cut and paste code, more pointers in the working of javascript, which native functions i could use, and what is the best way to set something like this up.
Thanx in advance
p.s. Maybe i want to also have a delay (100 ms or so) when the user is already using the menu for the items to show up. Will this be a lot more complex?
perhaps this can give you an idea: http://www.jsfiddle.net/dimitar/stthk/ (extracted it from another menu class I am working on and modded for delay for you as an example)
basically several interesting bits:
options: {
showDelay: 500,
hideDelay: 500
},
defines your delays on mouseover and out.
and then the bind for mouseenter deferred via .delay():
mouseenter: function() {
$clear(_this.timer);
_this.timer = (function() {
this.retrieve("fold").setStyle("display", "block");
}).delay(_this.options.showDelay, this);
},
mouseleave: function() {
$clear(_this.timer);
_this.timer = (function() {
this.retrieve("fold").setStyle("display", "none");
}).delay(_this.options.hideDelay, this);
}
_this.timer is a shared var that handles the deferred function - it gets cleared up on either mouseout or mouseover. if no event that matters takes place within the allotted time period, it will change the display accordingly, else, it will cancel the function.
this is for mootools 1.2.5 btw (storage system + elment delegation) but the principle remains the same for the bits that matter.
The stylish/anal way of doing it would be to fade in/out the menu. You do that with Fx.Morph where you morph the opacity css property and set the complete property to actually remove the div - notice that it's different to make this work in IE5-7.
The more basic/sensible way is to use setTimeout().
I am looking for the most proper and efficient way to bind Javascript events; particularly the onload event (I would like the event to occur after both the page AND all elements such as images are loaded). I know there are simple ways to do this in jQuery but I would like the more efficient raw Javascript method.
There are two different ways to do it. Only one will work; which one depends on the browser. Here's a utility method that uses both:
function bindEvent(element, type, handler) {
if(element.addEventListener) {
element.addEventListener(type, handler, false);
} else {
element.attachEvent('on'+type, handler);
}
}
In your case:
bindEvent(window, 'load', function() {
// all elements such as images are loaded here
});
I know you did only ask about how to bind events. But Ooooo boy the fun doesn't end there. There's a lot more to getting this right cross-browser than just the initial binding.
#d.'s answer will suffice just fine for the specific case of the load event of window you're looking for. But it may give novice readers of your code a false sense of "getting it right". Just because you bound the event doesn't mean you took care to normalize it. You may be better of just fixing window.onload:
window.onload = (function(onload) {
return function(event) {
onload && onload(event);
// now do your thing here
}
}(window.onload))
But for the general case of event binding #d.'s answer is so far from satisfying as to be frustrating. About the only thing it does right is use feature-detection as opposed to browser detection.
Not to go on too much of a rant here but JavaScript event binding is probably the #1 reason to go with a JavaScript library. I don't care which one it is, other people have fixed this problem over and over and over again. Here're the issues in a home-brewed implementation once inside your handler function:
How do I get a hold of the event object itself?
How do I prevent the default action of the event (eg clicking on a link but not navigating)
Why does this point to the window object all the time?
(Re mouse events) What are the x/y coords of the event?
Which mouse button triggered the event?
Was it a Ctrl-click or just a regular click?
What element was the event actually triggered on?
What element is the event going to? (ie relatedTarget, say for blur)
How do I cancel the bubbling of the event up through its parent DOM?
(Re event bubbling) what element is actually receiving the event now? (ie currentTarget)
Why can't I get the freaking char code from this keydown event?
Why is my page leaking memory when I add all these event handlers?? Argh!
Why can't I Unbind this anonymous function I bound earlier?
And the list goes on...
The only good reason to roll your own in these days is for learning. And that's fine. Still, read PPK's Intro to browser events. Look at the jQuery source. Look at the Prototype source. You won't regret it.
Something like that
window.onload = (function(onload) {
return function(event) {
onload && onload(event);
$(".loading-overlay .spinner").fadeOut(300),
$(".loading-overlay").fadeOut(300);
$("body").css({
overflow: "auto",
height: "auto",
position: "relative"
})
}
}(window.onload));
window.onload = function() {
// ...
};